Ophthalmic instrument



May 30, 1939. w, c, HARPER 2,160,359

OPHTHALMIC INS TRUMENT May 30, 1939- w. c. HARPER 2,160,359

OPHTHALMIC INSTRUMENT t Filed March 1o, 1937 8 sheets-sheet 2 'lli'.

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Filed March 10, 193'? 8 Sheets-Sheet 5 May 30, 1939- w. c. HARPER A 2,160,359

`OPKITHf-XLlvIC INSTRUMENT Filed March lO, 1937 8 Sheets-Sheet 4 v May 30, 1939. w. c. HARPER OPHTHALMIC INSTRUMENT Filed March lO, 1957 8 Sheets-Sheet 5 May 30, 1939. w. c. HARPER OPHTHALMIC INSTRUMENT 8 Sheets-Sheet 6 Filed March l0, 1957 May 30, 1939. w. c. HARPER 2,160,359

OPHTHALMIC INSTRUMENT Filved March 10, 1957 8 Sheets-Sheet 7 I N VEN TOR BY Wor CHQ/pez v 5x5/M S ATToRvEY May 30; 1939- w. c. HARPER` l 2,160,359

OHTHALMIC INSTRUMENT Filed March 10, 1937 8 Sheets-Sheet 8 I N VEN TOR Patented May 30, 1939 UNITED STATES PATENT ermee y American Optical Company,

, Southbridge,-l

Mass., a voluntary association of Massachusetts Application March 10, 1937, Serial No. 130,164

Claims.

This invention is directed to a myologic instrument for orthoptic training and exercise of the coordinating visual apparatus of a pair of eyes through causing a reallotment of innervation to the eye muscles by the brain. This application is a continuation in part of my copending application Serial No. 11,881, filed March 19, 1935, for Myologic instruments. The instrument is designed for the correction of heterophoria, vertical and horizontal, development yand renement of fusion, controlling of accommodation, and testing and measuring duction and p-horia. The instrument operates to cause a reallotment of innervation to the eye muscles by the brain by subjecting the eyes to an increase of prism power to balance the coordinated relationship between the accommodative and adductive functions.

Eye treatment for this result is recognized as standard practice. In such treatment, however,

the eyes are subjected to an increase of prism power and maintained during treatment under such increased prism power. This continual subjecting of the eyes during treatment to this increased unrelieved and constant strain is productive of seriously objectionable fatigue andV after-effects which, of course, gradually disappear but which necessarily limit each treatment to comparatively short periods and therefore increase the number of such treatmentsnecessary to produce the desired result.

The primary object of the present invention is the provision of an instrument of this character in which, during treatment, the-eyes are subjected momentarily to a strain period and then returned to a period of rest, the periods of rest and strain alternating and being automatically produced in the operation of the instrument. Thus, as the eyes are subjected to momentary strain and longer periods of rest alternately, constantly and successively produced, the fatigue and after-effects ofA the treatment are negligible so far as any disagreeable conditions are concerned and thus each particular treatment may be continued for a greater period of time than earlier possible, with the result of materially reducing the Anumber of treatments required to reach the desired result.

A further object of the invention is the production of an apparatus in which the amount of prism power being used or capable of being used is completely within the control of the operator an-d can be adjusted to any desired maximum or minimum limit, with the further provim sion of means whereby the operator is visibly in- Vof the eyes to widenthe coordinated relationship formed at all times of the amount of prism power being utilized. l

A further object of `the Vinvention is the provision of anl instrument of the above character having illuminating means for the respective Iix` ation means which may be synchronously or alternately flashed and so arranged that the said synchronous or alternating flashes may be timed to take place at predetermined intervals or sus-A tained for predetermined periods during the varying of the prism power beforethe eyes.

A further object ofl the invention is the provision ofr means for controlling accommodation during the eye treatments.

A further object of the invention is the provision of an instrumentv of this type wherein the amount of prism power is automatically and repeatedly 'varied to create the necessary motion or lock between the accommodative or adductive functions, thus permitting the operator to change the phorias and ductions in any direction that may be desired, the said prism. power being variable orl adjustable by controlled amounts during the operation of the instrument or when the said instrument is not in operation.

A further object of the invention is the use of scales and pointers, with the .scales graduated according to the prism dioptry to permit the operator to be advised exactly of the amount of prism power being used at `any period of treatment in the correction of both Vertical and horizontal balance as well as the amount of automatic change in such power that is being used; this use of the scales and pointers permittingthe operator to accurately follow any change in the prismatic power and thus be advised as to the extent of the phorias and ductions at any time.

1 A further object of the invention is the provision of an instrument of this character in which the test implement may be in the form of a revolving target illuminated by reflected light or a ixed translucent target illuminated by transmitted light, together with means for controlling the degree of illumination to suit the requirement of the eyes of the patient being treated.

A further Objectis to provide an instrument oi the above character with adjustable mirrors for increasing or decreasing the prism power before the eyes and which may be tilted vertically if desired.

The invention in the preferred form is illustrated in the accompanying drawings, in which: l

Figure 1 is a plan view of the instrument, partly broken out. Y

Figure 2 is a plan view of the instrument with the cover removed.

Figure 3 is a bottom plan view of the upper section of the case, showing the driving means.

Figure 4 is a broken plan showing the mounting and connection of the mirrors.

Figure 5 is a side view of thesamel Figure 6 is a front View of the same.

Figure '7 is a broken front view of the case,'

showing particularly the sight openings and chin-rest. i

Figure 8 is a view in elevation, partly in section, showing the driving means forthe rotat-` ing targets.

Figure 9 is a side view showing the means for adjusting the chin-rest.

Figure 10 is a detail view, partly in section, showing the eccentric mounting for. operating the mirrors. y Figure 11 is a plan'of the same.

Figure 1 2' is a plan, of the disk showing the adjustment openings for the eccentric.

Figure 13 is fatevier' fof modified target for use with the appaiatuls'. A i Figure 141s hroke Plan of a modified form of 'mirror operatir'1g mechanism.

Figure '15 isa` s eel of the saine.

' Figure 1.6 is a face View of the means for manually adiilsiiile'te miner @rientrin- .Figure 17 is a perspective View of a modified form. of instrument 'having incorporated therein a ilashsyst'e'm and other modiied'details of construction.

Figure 18 is a plan vlew of the instrument shown' in Figure 1A7 having the greater portion of. the top thereof remoyed to Vshots/ the' details ofk construction.4 4 f y. 'e 191s@ Schematic new or innerer and motory control system.

' 4liglireZil.isv an enlarged fragmentary sectional viewtaken online A211 l f2!) fof y18.

Figure 2l is an enlarged fragmentary sectional viewtakenf as Online 2I-f2fl' of Figure 17 and showing fthe bearing means and'pivot support for the lmirrors yand mirror operating means. Thefinstrumentis mounted on ay caseI havingr aninternediatehorizontal partition 2. The case is divided into anflilper'section t., and a lower sectfior'iv 4, the partition 2' forming the bottomr of the upper sefctionl'A The forward wall of the case inclins inwardly from eachv en d to a central opening in upper section and the top of theuppe'r section. is, formed as a central fixed portion 'S coectensiveN xjviththefopening 5 beyond which Yired portion'thetop'ineludes the. hinged coverA portions "If "Therear 'part of the central fixed'portiont has a hinged cover portion 8 closing an. opening 9.. in suchfiiged portion 6.

"Abracket Ill vertically bridgesv the opening 5 at the -central portionthereot the'lower end of the bracket being securedI to the partition 3 and the upperend'to a plate II bridging a recess I2 in ,the` forward edge of thefixed portion E of the top, Abar I3 is'piv'otallyl supported intermediate itsends, .as at [4, the lewerend of the bracket I Q overlies is secured to the partition The forward Vend of the,y han@ isslotted to reeve'the lgwr @ed Of esiliati. 1.5 the upper end of which extends through an enlarged opening I6 in the plate II. The lower end of the shaft I5 is guided in an arcuate` slot I5 "i n the lower end of the ,bracket I0.`

The shaft lsu'pports the forward ends of mirrors Il and I8, the opposite ends of the mirrors exten-ding within the upper section of the case to dispose the mirrors in definite relation to brackets which will be later described. One of the mirrors, as Il, is rigidly secured to the shaft i5 through any appropriate connection while the other of the mirrors, as I8, is swingingly supported on the shaft I5. Mounted in alignment with the mirror support shaft I5 is a motor mechanism here shown as a clock-work I9 which is bodily adjustable toward and from the mirrors through the medium of a threaded rod 25 cooperating with a nut 2l secured to the rear Wall of the case, the inner end of the rod being connected to the clock-work and the outer end being provided beyond the case with a finger Wheel 22.

A shaft 23 of the clock-work I9 is provided on its upper end Vwith a disk 2li on which is eccentrically pivoted at 25 a second disk 26. The disk 26v is provided with a pin 2? extending therethrough and adapted to engage any one of a series of openings 2B in the disk 215i, whereby the degree'of` eccentricity of the second disk 26 may be selectively varied for a purpose which will later appear. Encircling the second disk 28, here inafter termed the eccentric, is a hand 29 connected bya rod l3!) to one terminal of a bar 3|, the opposite terminal of which is swingingly supported in the remote end xvallof the case, the bar 3,! being of considerable length to cause the free end to which the rod v3? is connected to moveV substantially in a straight line under the operation of the eccentric.

The free end. ofthe' bar 3i is connected by tie bars 372 tothe respective mirrors i and I8 on f y the relatively adjacentor non-reflective surfaces and at points in'advance of the pivotally supportedlends of themirrors. A spring 33 is interposed between thetie bars 32 to insure a proper spreading mevernent of the mirrors under the action of the eccentric. y

' From the above construction it'will be understood that `with the clock-work or other motor I9 in operation, the eccentric willr cause the tie bars 32 torswing the mirrors on their pivotal support or shaft I5 toward and from each other in regirilar uniform degrees of movement and in regular uniforml periods of time. The degree of movement may be changed at will by adjusting the eccentricity of the eccentric 26 through the use oi a selected opening 23 but the period of time of movement remains the same, as predetermined by governor setting.

The ability toadjust the normal angular relation of the mirrors is a highly important detail of the present invention, as will later appear, and it is 4quite obvious that this angular relation may beV mechanically changed through manual adjust Inent of the threaded rod 20, in which adjustment the motor eccentric and connections between the eccentric and mirrors are bodily moved in one direction or the other withthe result of varying the angular relation between; the mirrors, as will be obvious.

A target 34 is mounted for rotation on each end wall of the upper section 3 of the case, the target being preferably in the form of a metal or other disk having a toothed periphery. Each target is, of course, within the reflective range of the adjacent mirror and on each target is preferably provided a distinctive vision area in the form of ajewel or like element 35, preferably though not necessarily distinctively and vividly colored. The jewel elements ofthe respective targets are set in relatively diametrically opposite positions.

Mounted inthe forward wall adjacent each target and between the target and its mirror is a source of illumination in the form of an electric bulb 36 and the circuit 31 for each bulb is controlled by a switch 38 and includes a series of selective resistance 39 of any usual or conventional type manually controlled by a switch arm 45, so that either or both sources of illumination may be graded in intensity as desired.

Secured upon the shaft I5 immediately above the plate II is a toothed wheel 4I meshing with a barrel gear pinion 42 secured upon a shaft 43 supported at its lower end in the plate II and adjacent its upper end in an offset bracket 44 carried by the plate II. Secured upon the upper end of the shaft 43 is a pointer 45, the free end of which plays over a scale 46, the divisions of which extend in both directions from a neutral or zero point and are graduated in exact accord with prism dioptry. A spring 41 coiled about the shaft 43 insures accuracy and steadiness of movement of the pointer.

In testing and training the eyes by the use of the present instrument, it frequently happens that the patient will indicate a condition of nonvertical balance, that is when the test reaches a point of diplopia, the two objects seen are noton substantially the same horizontal line. The present instrument provides for a correction of this condition within the instrument itself by changing the normalV true horizontal relation of the mirrors to raise one image and correspondingly depress the other until a point ofl vertical balance is obtained. This is secured through physically shifting the lower end of the shaft I5 in one direction or the other to correspondingly shift the mirrors.

This is accomplished through a shaft 48 xed at its lower end in the forward end of the bar I3 and extending through an opening in the'upper portion of the bracket I0, with such Vopening permitting a slight swinging movement of the shaft. The upper end of the shaft is provided with a pointer 4Q moving over a scale 50 graduated as is the scale 45. The pointer 49 is to be moved by hand and the resilient turning movement of the shaft ll, which is fixed at its lowerend in the bar I3, will swing this bar on its pivot I4 and .at the point of double vision or the image seen by the left eye at the point of double vision is moved either upwardly or downwardly so that the images seen at the point of double vision vare adjusted to' be on substantially the same horizontal line.

The opening 5 is bridged and substantially closed by a removable spectacle plate 5I formed with vision openings and with external supports 5i. to removably receive a frame 53 in substantially eye-glass shape and carrying lenses 54 through which the patient views the reflections inthe mirrors during the test and training. The removability of the frame 53 permits the application of lenses of diiferent character'and power if necessary to suit the eyes of the patient being treated at the moment.

In order to support the eyes in accurate position with respect to the lenses 54, a chin-rest 55 is arranged immediately below the plate 5I and adjustable for accuracy in positioning the eyes of a particular patient, that is the chin-rest is supported upon a rod 56 guided in a support on the lower edge of the. case connected to a lever 5l Y as the pointer is operated in and by .ment of the shaft I5 and as the shaft is moved pivotally supported on the bottom of the case and extending transverse the same with the rear end threaded to cooperate with a threaded rod 58 tov be manually operated at will and to there- Y by raise or lower thechin-rest as may be needed in the particular instance.

It will be noted that the projection of the image or jewel 35 on each taget 34 is seen in the mirror by reflected light as the source of illumination 35 is between the mirror and target. If' desired, the image may be viewed by transmitted light, for which purpose the covers I may each be formed with a slot 59 between the source of illumination 35 and the proximate mirror, the upper surface of the partition 2 in line with the slot being` formed with a guideway 65 to receive and support frames 6I carrying transluscent sheets 62 upon which any desired characters may be printed or otherwise affixed to vary the type of the visual reflection, as may be desired to avoid monotony to the patient or for special test purposes. The targets 34 are driven by a shaft 63 extending longitudinally in suitable bearings on the bottom of the partition 2, each end of the shaft 63 being provided with a gear 64 one directly and one inlQ directly engaging and operating the targets in synchronism. The shaft 63 is operated by an electric motor 65, the-circuit of which is controlled by a switch 66 and the motor shaft is formed or provided with a worm 5! engaging a worm gear 58 on an auxiliary shaft 69 which extends parallel to the shaft 63 in one direction from the motor and is terminally provided with a belt wheel 10 connected by a belt II with a belt wheel I2 on the adjacent shaft 68.

A belt tightener in the shape of a wheel 'i3 bearing on the belt and controlled through a hand lever 'I4 capable through means indicated at15 of being locked in various positions of adjustment insures proper predetermined speed of the targets. The end of the auxiliary shaft 5S opposite the beltwheel I5 is connected through gearing I5 with an appropriate governor ll. If desired and as preferred, the speed of the motor may be controlled through an adjustable resistance switch 18.

With the parts arrangedand correlated as described and assuming the usev of the targets for the test and training, the motor or clock-work i5 is energized or wound causing the pointer 45 to move over the sca-ie 5 tcy the limit in one 'direction or the other from the zero point of such scale Vto the limit determined by the set of the eccentric 26. It is obvious that when the pointer has reached this limit, it will immediately return over the scale to the zero point. Of course,

ie moveby the eccentric through the movement of one of the mirrors, as l'l, and through the similar cori-` nection from the eccentric to both mirrors I'I and I8, the actual operation of the eccentric causes the mirrors to swing in a horizontal plane from the shaft I5 as a center synchronously in opposite directions. That is to say, the mirrors move their free ends alternately toward and from each other to thus vary the prism power to which theA vision is subjected, the extent of this prism power being indicated by the movement of the pointer 45 over the scalev 45.

The patient, with his chin resting in the appropriately adjusted chin-rest 555 and his eyes close to and viewing the interior of the case through the lenses 54, sees the targets and particularly the jewels 35 thereon under binocular vision as a image into two images turning in or out.

single image. .If the ltwo .eyes are coordinating properly, the single image is maintained Vduring the movement of the pointer throughout the set limit of travel, whereupon vthe operator will adjust the clock-work bodily through the manipulation of the rod 20 to thereby spaced the free ends of the mirrors farther apart at their point of closest approach than in the origin-al setting. That is to say, in the swing of the mirrors under the action of the eccentric in the initial setting, their free ends are spaced a deiinite ldistance apart when the pointer is at the zero position of the scale and by adjustment of the clock-work or motor toward or from the mirrors, this normal spread or spacing of the free rends of the mirrors4 may be reduced or increased according to the `direction of adjustmentV of the clock-work.

As the pointer travels in the same direction as the movement of the mirrors under the eccentric, it will be apparent that when the clock-work is adjusted bodily toward the mirrors, their initial spacing will be increased and thus as the mirrors move in response to the eccentric movement, the pointer will travel tothe right of the zero point, as viewed from the front of the case, over the scale, whereas if the clock-work is adjusted to decrease the initial spacing between the free ends of the mirrors, the pointer .will travel to the leftl of the zero point, as viewed from theV front of the case.

If, during the test, it is found that the visionof the patient beholcls the views of the targets as a single image, the clock-work is adjusted to cause the pointer to swing over the scale in the same direction in which it Ahas been moving but to a greater extent. Of course, the eccentric compels identical movement of the pointer in any one setting of the clock-work, so that in the new setting of the clock-work, the pointer swings over the same area of the scale as in the initial setting, but as the clock-work has been adjusted to increase the reach of thev pointer on the scale, the pointer in its return from its maximum scale position to the minimum will not, of course, reach the zero position. In other Words, if theinitial swing of the pointer is from zero Vto 10 and the clock-work has been adjusted to causethe pointer in its maximum positionto reach 15, the pointer in its return will have its minimum position at 5.

During the test of the particular-patient, the adjustment of the clock-workr is continued to increase the maximum swingY of the pointer until the patient advises that the image-at or approaching `the maximum swing of the pointer is seen as two images. This is a condition of diplopia and indicates that the eyes. are not coordinating to hold binocular vision but that one or the other of the eyes are -at the point of prism power indicated at the break of the single It is for the purpose of correcting this lack of coordination that the present instrument is devised, for it is a well known fact that under a proper training exercise a reallotment of innervation to the eye muscles by the brain may be brought about to widen the coordinated relationship between the accommodative and adductive functions of the eyes and thus create an incentive to binocular vision beyond the possible range of such vision before treatment.

It is, of course, to be remembered that the mirrors are continually moving to vary the prism power from the minimum to the maximum as indicated by the range of the pointer and as the clockwork has been adjusted to carry the prism power to a point slightly beyond a condition of diplopia in the particular patient, it will, of course, be apparent that as the mirrors move to their position of minimum prism power in the particular adjustment, the eyes will have the greaterportion of 4this range for binocular vision. Thus, the mirrors, or more particularly the prism power, are continuously reciprocated from a minimum to a maximum at which or approaching such maximum a condition of double vision is apparent.

The treatment over this range is continued and incident to the inherent tendency on the part of the patient to maintain binocular vision, it will be found that gradually the patient can maintain binocular vision up to the point of the maximum prism power ofthe mirrors in their then setting. When this condition is reached, a course probably covering several treatments, the swing of the mirrors is increased, that is the prism power is increased, again carrying the vision at the maximum range of prism power to a point of diplopia. The treatment is continued through this range until gradually the patient maintains binocular vision throughout the range. a series of treatments, therefore, coupled with the, incentive to binocular vision in the patient,

Vthe coordinated relation or lock between the accommodative or adductive functions of the eyes muscles of the eyes and the nerves controlling the muscles, with the effect that the patient is` seriously inconveniencedy thereby. In many instances, the strainresults .insevere head pains and at times more or less bodily derangements lwhich areA highly objectionable. This heretofore unsurmountable `difficulty has compelled com-'l paratively short treatments and thus a very extended series Yof treatments-Tte reach the desired result; It isa particular andimportant function of the present instrument to overcome this difficulty and to avoid any serious after-effects on the patient, permit longer single treatments without after-effects, and thus lvery materiallyshorten the time of complete treatment in a particular instance. .This is gained through the fact that when the prism power has been carried to the point loi diplopia of vision, it is maintained at this pointf only during l,theperiod of movement of the mirrors, increasing the, prism power to a is immediately reduced and will.remain duringy the swing of the mirrors and pointer from the maximum to theminimum and from the minimum toward the maximum in a position permitting binocular vision. As during thisperiod of binocular vision, the eyes are under no strain other than a normal one and remain under strain only during the periods of maximum power, which are of course very short due to the substantially constant movement of the mirrors, the eyes are under strain but momentarily and during the remainder of the periods are at rest or under no strain other than the normal one. Thus, in the particular instrument, there are momentary periods of strain and longer periods of rest, al-

Through ternatel'y and constantly repeated. Therefore,

while the effect of the strain periods is exactly the same as under the constant prism power change heretofore practiced,there are periods of rest between each period of strain which so changes the effect on the eye muscles and nerves supplying them as to materially reduce if not completely eliminate the after-effects of the treatment.

Thus, the alternate periods of strain and rest to which the eyes are subjected during the treatment by this instrument constitute a very material advance in this art, for thereby the aftereffects of the continued eye strain incident to the previously practiced methods is substantially eliminated, permitting the particular period of treatment to be maintained for a greater length of time than hereto-fore possible and thereby reducing the number of treatments necessary to reach the desired result. Of course, by mirror adjustment as described, the correction of coordination may be provided where the eye or eyes turn in or out, the same operative functions being carried out in each instance.

1f at the point of diplopia, it has been found that the two images are not aligned horizontally when viewed through the lenses, an indication is thus presented that the eyes are out of vertical balance and the pointer i9 is manually adjusted to raise one mirror and correspondingly lower the other mirror until the two images are substantially in the same horizontal plane. This condition, from lack of vertical balance, is simultaneously corrected by the use of the instrument Yas is the horizontal balance as above referred to.

' The important detail of the present invention 1s in the provision of subjecting the eyes to alternate periods of strain and rest automatically with each period of rest and period of strain con- 40 stantly and uniformly repeated, with the effect of eventually coordinating the visual control of .ya pair of eyes by compelling a reallotment of innervation to the eye muscles by the brain, with the additional function cf adjusting the degree of strain as the lack of comfortable coordination is gradually corrected.

If, during the test, the vision of one eye is found to be stronger than the other, they may be brought to substantially equal vision effect by the control of the degree of illumination of the respective bulbs 35 through government of the particular resistances 39 in a well understood manner.

With the above instrument any character of targets or test devices may be used, provision being made particularly herein for the use of revolving targets or fixed test devices, as indicated at 92. The character of the test devices depends, of course, upon the nature of the treatment. The character of the control of the drive may be conventional, the clock-work may be substituted by a motor providing for proper movement of the mirrors and permitting necessary adjustment thereof, and any conventional means may be provided to control the degree of illumination.

As alternative means for operating the mirrors to permit the use of a single driving motor for the entire apparatus, the construction used in Figures 14, 15 and 16 is provided. The shaft 99 is provided with a cone 'i9 rotatable with the shaft but axially adjustable thereon. The cone has frictional driving engagement with a disk 80, the bearing 8| of which is supported in a spring strip 82 fixed at 83 to the under side of the partition 2. The cone 19 is adjusted through a 75v finger lever 83 pivoted at 84 and terminally engaging a collar rotatable on the cone, one end of the lever projecting beyond the side wall of the case, as at 85, for convenient manipulation. The cone may thus be adjusted longitudinally of the shaft 69 to drive the disk 80 at selected speeds, the disk yielding under cone adjustment through the spring support 82 to insure the driving frictional contact. A hollow shaft 86 is secured to and passes through the disk 80, this shaft having eccentric bearings at each end, as at 81. The

shaft 86 is hollow and a drive rod 88 extendsl therethrough and is operated thereby. The end of the drive rod has a disk 89 with an offset outstanding pin 90, to provide a crank movement in the operation of the disk 89. The shaft 86 extends beyond one side wall of the casing and is provided with a finger lever 9| by which the shaft may be turned. This lever is of spring type and has a pin 92 adapted to seat in any one of the series of openings 93 in a plate 94 secured to the outer side of' the wall of the hollow shaft. By this means the shaft may be turned in its successive bearings to vary the throw of the crank 90, the mountings being such that it is possible to dispose the crank pin 90 in the center of rotation of the shaft and thus interrupt any crank movement. I

The crank pin 90 is connected by a rod 95 which has yoke connection at 96 with a lever 91, extending through the partition 2 and swingingly connected to said partition at 99. The upper vend of the lever 91 is formed with an opening for the passage of a shaft 99 and is slotted at |00 to receive a ring |0| which is secured to the shaft 99. This construction permits the shaft 99 to rotate freely in and with respect to the lever 91 while at the same time insuring that the movement of the lever will correspondingly reciprocate the shaft 99. One end of the shaft extends `beyond the side wall of the case and is provided with a linger disk |02, whereby the shaft may be rotated at will. The opposite end of the shaft extends freely through a bearing |03 and beyond the bearing is threaded at |84 to cooperate with a sleeve |05 mounted on the threaded portion and obviously movable toward and from the bearing |03 in accordance with the direction and to the extent that the shaft 99 may be rotated through the finger disk |02. The sleeve |05 has a rigid depending brace |06 which at the lower end is extended laterally, as at |01, and is accurately guided through an opening |08 formed in the upright |09 which supports the bearing |03. The sleeve |05 is provided with an upstanding pin I0 to which the mirror operating arms 32 of the construction previously described are connected. Beyond this point, the construction is as previously described.

According to the cone adjustment for speed, the shaft adjustment for crank throw and the operative adjustment of shaft 99, it will be apparent that the speed of movement and the maximum and minimum divergence of the mirrors may be readily controlled exactly as through the clockwork motor I9 of the previous form.

In Figures 18 to 20 inclusive, there is shown a further modified construction having targets ||5 rotatably supported at ||6 within the instrument housing |1. The targets ||5 are each provided with image producing means, such as a brilliant or jewel |8, having a plurality of facets disposed at different angular relations to each other. The targets ||5 are rotated about their pivots ||6 by means of sprockets ||9 connected by chain members |20 to sprockets |2| secured adjacent the opposite ends of the shaft |22. The shaft is in turn rotated by means of a pulley |23 driven by a belt |24 connected with a pulley |25 to a shaft |26 driven by a motor |21.

'I'he targets ||5 are rotated in opposite directions so that when the images of the brilliants |8 are reiiected by the mirrors |28 they will appear as being both rotated in the same direction. The targets ||5 are illuminated by spaced electrical lamps or bulbs |29 and |29. The said lamps may be continuously illuminated or synchronously or alternately flashed by means of an electric system, such as shown in Figure 19, having incorporated therein positive manually controlled switch means |30 and |3| and automatically operating make and break means |32.

It will be noted that when the blade |33 of the switch member |30 and the blade |34 ofA the switch member |3| are in engagement with the contacts |35 and |36 respectively, the sources of illumination |29 and '|29' will be continuously illuminated, particularly when the main switch member |31 to the source of electrical energy is closed. The intensity of the sources of illumination may be separately controlled or varied by means of suitable rheostats or the like |38 and Should it be desirable to have the source of illumination |29' flash while the source of illumination` |29 is continuous, the blade |34 is engaged with the contact |v of the switch |3|. 'I'his causes the electrical energy feeding the source of illumination |29' to flow through the circuit |4|. The flashing is brought about by the successive engagement of the contact member |42 with the contact |43. By reference to Figure 20, it will be seen that a rotating cam member |44 carried by the shaft |45 intermittently causes the contact |42 to move into and out of engagement with the contact* |43 through the resilient action of the support |46 of said contact |42-l The period of illumination is controlled by'theduration of the engagement or disengagement of the contacts |42 and 43. This is controlled by the adjustment of the screw support` |41- by means of which the contactl |43 may be moved toward or away from the contact |42. This may also be controlled by varying the speed of rotation ofv theshaft |45. This is brought about by reducing or increasing the speedr of the drive motor |21 through the rheostat |48'.

Should it be desirable to have the sourcev of4 illumination |29 synchronously flashed with the source of illumination |29', the bladel |33 of the switch |30 is moved into engagement with the contact |49; It will be seen that this contact |49 is connected through the line |50 with the contact |43 so that the circuits controllingv the illuminationof both sources of illumination |29 and |29' are opened and closed simultaneouslyA through the engagement and disengagement of the contacts |42 and |43.

Should it be desirable to have the sources of illumination |29 and |29' alternately ash, the blade |33 of the switch |30 is moved into engagement with the contact |5|. This contact |5| is connected through the line |52 to a Variable contact member |53. By again referring to Figure20, it will be noted'that the contact member |53 is placed on the side of the contact |42 opposite the contact |43, so that when the cam member |44-is rotated, the contact |42 is moved from engagement with the contact |43 into engagement with the'contact |53. This causes' the circuit-|4f| to be deenergized, therebyshutting offY the source of illumination 29', and the ycircuit |52 to be energized to illuminate the source of illumination |29. The duration of the period of illumination of the source of illumination |29 is controlled by the screw member |54 which may be adjusted tomove the contact |53 to varying spaced relationl with the contact |42. This causes the contacts |53 and |42 to remain in contact with each other in variable periods of duration. It willv be noted, therefore, that as the cam |44 rotates, the sources of illumination |29 and |29 will be alternately and successively illuminated. As previously stated above, the intensity of the sources of illumination |29 and |29' is separately controlled byrheostats |38` and |39; This is true in all instances.

When it is desired to' disconnect one or the other of said sources of illumination, the blades |33 and |3'4'are moved into engagement with the contacts v|55 and |56'.

The motorl |21' is of the reversible type, being connectedthrough' a reversible switch |51 to the main feed lines |158' and |59 bymeansof the lead wires |60 and |"6"|. Suitable lead wires |62 and |63'are connected to=themotor circuit for rotating the motor in one direction and lead wires |64 and |65'v are connected to the motor circuit for rotatingl the motor in'v the opposite or reversed direction. In order to control'the speed'of rotation or balance the speed of' rotation of the motor in botlrdirections, a suitable resistance unit |66 is placed'in th'e'circuit |63. This resistance unit is used to reduce the current ilow to the motor when the said motor'is rotating in its normal direction so as to cause the' speed of rotation of the motor when reversed to be equivalent or substantially equivalent to its speediin normal direction of movement. This is due to the fact th'at when the direction of' movement ofA a motor is reversed, the speed isv automatically cut down; so in order to balance the. speed' of rotation, the in-v itial normal movement' of the motor is reduced through theY resistance unit |66. The speedAv of the motor in either direction may thereafter be controlled through the rheostat |48. The reverse action of the motor is brought about by shifting the contactsY ofl the feed linesv |60 and |6| from engagement with the contacts connected withA the lead wires |62 and |63 to the contacts connected with the lead wires |64 and |65 and vice versal The mirrors |28 are hlngedly supported on a bar member |61 so that they may be swung toward and away from each other inl a horizontal plane. The saidbar member |61 is pivotally attached at |68 to a bracket |69, see Figure21, carried'by the base of the instrument; This is to enable the mirrorsv |28'to be swung or tilted'in a vertical plane. The movement in the horizontal plane is brought about through linkV members |10 pivotally connected at |1| adjacent one end thereof to the mirrors |26 and at |12 adjacent the opposite end thereof to a bracket |13. The bracket |13 is pivoted at' |14 to a member |15 having a portion |16's1idable within'a bearing |11 carried by the bracket |69. The portion |16 of the member |15 is'm'oved'longltudinally of the bearing |11 by a rod |18see Figure 17, threadedly connected at |19t`o the member |15.

The rod |18 'is rotatably supported in a sleeve |80, which in turn is pivoted at' |8| to a yoke |89, see Fig. 17. The sleeve |60-is held against movement longitudinally ofthe rod-|16 by suitable collars |90 secured to the rodby setl screws, pins or theV like. The yoke is'pivotally connected' at |9|' as" l to a bracket |92 secured to the base of the instrument. The yoke has a link member |93 attached thereto intermediate its ends as indicated at |94. The link member |93 is attached adjacent its opposite end to a eccentric crank member |95. The crank, as shown in Figures 17 and 18, is secured to the end of the shaft |45 and is adapted to be operated by the rotation of the shaft M5. The crank member |95 is so constructed that its throw is variable, that is, its operationis similar to that of the member 89, shown in Figure 14, and which has been previously described in detail.

The shaft |45 is rotated by means of a gear |96 which meshes with a gear |91, which is in turn driven by a disk |98 which its in between two friction disk members |99, which are keyed to the main drive shaft |25. The disks |99 are forced into frictional engagement with the disk |98 by means of the springs |20 and 12| respectively. The gear |91 and the disk |98 are carried by a bracket 200 which is mounted to swing on the shaft |45. The object of this arrangement is to provide means whereby the disk |98 may be moved toward or away from the shaft |26 to increase or decrease the speed of rotation of the gear |91. The bracket is swung toward or away from the shaft |25 by means of a link member 20| pivotally connected at 202 to the base of the machine and having a pivotal connection at 203 with a projection on the bracket adjacent one end thereof and with a combination slide and pivotal connection 204 of a screw adjusted member 205 adjacent the opposite end thereof.

The member 205 is threadedly connected with a threaded bar member 206 and is adapted to move longitudinally of said bar member 206 when it is rotated. This causes the link member 20| to be swung about its pivot 202 and in turn swing the bracket 290 on the shaft |45. This arrangement increases and decreases the speed of rotation of the crank member |95 so that the extent of the oscillation of the mirrors |28 in the horizontal plane may be controlled.

The amount of oscillation of the mirrors |28 is determined by means of a scale 200', see Figure 18, and indicator 201. The indicator 201, as shown in Figures 17 and 21, is operated bymeans of a gear 208 which meshes with a rack 209 formed on the side of the slide |16. When the slide |16 is reciprocated back and forth through the action of the crank member |95 to oscillate the mirrors |28, the gear 208 is simultaneously rotated and causes the indicator 201 to move a predetermined amount over the scale 205', the scale 206 being so graduated as to indicate the extent of said oscillation in terms of prism diopters.

To initially introduce the amount of prism power desired before the eyes of the patient prior to the oscillation of the mirrors or to vary the amount of prism power before the eyes of the patient during the oscillation of said mirrors, the rod |18 is rotated by means of the thumb nut 2|0. This causes the threaded portion |19 to be threaded into and out of the member |15 and thereby increases or decreases the angle between the mirrors |29. The amount of adjustment will be recorded by the scale and indicator means 209 and 201. This arrangement, therefore, provides means whereby the amount of effective prism power desired before the eyes may be introduced, either base-in or base-out, by adjustment of the screw member |19. The extent of oscillation to further increase or decrease the effective prism power as desired is introduced through the adjustment of the swing of the crank member |95. This crank member may be adjusted to the dead center of the shaft |41 so that there will be no oscillation of the mirrors, or it may be adjusted to its extreme throw to introduce a Vconsiderable'oscillatory movement to said mirrors. This adjustment is accomplished by means of the manually operable handle member 2| I.

The bar member |51 supporting the mirrors |28 is swung about its pivot connection |68 to the bracket |69 by movement of its lower end 2|2 longitudinally of a groove 2|3 formed in a base support 2|4. The lower end 2|2 is pivotally connected at 2|5 to a slide bar 2| 6 having a rack portion 211 meshing with a pinion 2|8. The pinion 218 is mounted on a rod 2|9 which is adapted to be manually operated by a thumb nut 220, see Figures 1'1, 18 and 21. The thumb nut 229 is provided with an indicator 22| which moves over a curved scale 222. When the thumb nut 220 is rotated to the left or to the right, the mirrors |28 are tilted in a vertical plane about the pivot 88. The bracket |13 is simultaneously tilted about the pivot |14 which is in axial alignment with the pivot |88. 4 The amount of movement is determined bythe position of the indicator 22| relative to thescale 222. The scale 222 is preferably graduated in prism diopters.

The mirrors |28 are preferably supported within a chamber formed by a back wall 223 and side walls 224 and 225 so as to conceal the working mechanism of the instrument from view during use. The side walls 22s and 225 are provided with open areas 226 and 221 through which the rotating targets H5 are viewed. 'I'he side walls are also provided with vertical slideways 228 and 229 for supporting auxiliary test charts or targets in alignment With the openings 226 and 221.

The housing ||1 of the instrument is provided with sight openings in the front thereof through which the reflected images of the test target are Viewed. Suitable clip means 239 are provided adjacent said sight openings for supporting corrective lenses or other suitable means 23| in alignment with the said openings, see Figure 18. A suitable adjustment chin rest 232 is also provided for supporting the head of the patient in alignment with said sight openings. IThe corrective lenses 23| are supported in suitable holders by means of which they may be interchanged, if desired.

During the use of the instrument the patients head is supported with his eyes aligned with the sight openings of the instrument. He` is adapted to view the images of the rotating fixation means |18 in the mirrors |28. The said mirrors are adapted to be adjusted under normal conditions of use until the patient reports comfortable single binocular vision of the images. The machine is then set into operation. The swing or oscillation of the mirrors as controlled by the crank |95 and other associated mechanism is then adjusted to control the extent of the oscillation of the mirrors. The amount of effective prism power, either base-in or base-out, is then introduced by rotation of the rod |18 by turning the thumb nut 2|0. This varies the angle between the mirrors and also produces an eifect similar to that of placing prism lenses, either base-in or base-out, before the eyes depending upon the adjusted positions of the mirrors. The oscillation of the mirrors produces an effective prism power which is continually increased and decreased within a instrument provides means whereby several treatments, tests and measurements may' be accomplished. Some of the treatments are as follows:

Convergence and divergence treatments, version treatments, retinal stimulation treatments, stereoscopic treatments, vertical and horizontal treatments, accommoda-tiveV treatments, phoria tests, tropia measurements, either vertical or horizontal, disassoc'iation technique, and ductin measurements, etc.

The above treatments, etc., are set forth with a View to distinguishing some of the accomplishments yof the instrument. It is to be understood that the above treatments, etc., may be accomplished separately or simultaneously.

' ments. l y

lumination, o1" may be brought about by adjust-` The convergence and divergence treatmentsare carried out substantially as follows: It isV to be assumed that the patient isl suitably positioned fbefore the instrument. The sources'of illumina-v tion |29 and |29 are turned on. Suitable targets are then exposed to the patient. These targets are preferably supported in the slide supports *2'28 and 229 in alignment with the openings 226- and '-221 in the side walls of the mirror housing. Suitable lenses 23| for accomniodative; control are placed before the eyes. The mirrors |28 are then adjusted by turning the thumb nut 2H)` to Vary the angle therebetween in the horizontal plane;

' and/or by turning the thumb nut 220 to tary tirel angle in the verticalV plane until the patientV reports easy fusion of the targets. The instrumentv is then set into operation at desirable speed-as controlled by the rheostat. |48.

If desired the mirrors |28 may bej o's'cillate'dtry the rotating crank member and' associatedt mechanism to produce an increasing-A and decreasing effective prismv` power before the eyes.- The amount of effective prism displacement is` controlled by operating the hand lever 2| which varies the throw of the crank |95; The abovetreatment may be performedl either with sttionary targets or with targetshaving eccentrically rotating fixation means thereon.

The amount of effective prism power may, if desired, be increased or decreased either through the plus or minus range during the oscillation-of the mirrors by rotation of theV thumb nut 2|!) which either increases or decreasesv the angle between the mirrors separately of the oscillation function thereof.

In addition to the above, the speed of operation of the instrument may be Varied.'`

It is also possible during any of the above arrangements to introduce vertical compensations by manually rotating the thumb nutw220 back4 and forth predetermined amounts. This gives vertical duction exercises.

The above exercises may be given rst with the targets rotating in one direction and with the targets set to rotate'inY a reverse direction toA change the order or pattern of cordinationrespense. This is brought about by reversing' the' switch member |51.

It is also possible to ontroduce break and re'- covery treatments with any of the abie arrange- This is brolight about by shing the ilment of the effective' prisii power bforlth'yes' yso that it is possible for th'epatirlt at O'Ii'e'point" of os'kz'illatin"A of the' mirrors' to fuse the images, and at another peintl of oscillation it will be impossible for the patient to obtain fusion. This latter arr Veir'ient is brought about by adjusting tlie between the mirrors by rotation of the thu-m nut 2|`|J to such a position that there will be: an atoinatio change between the break recovery points.

The flashing of thesources of illumination may be synch'rhous and so timed that it will occur at theV instances when the greatest amount of prisin pwen'either base-outer base-in, is before the eyes, or at the instance when the least amount of'fizir`isnfiV power, 'either base-out or base-in, is bef-*ore the" eyes or at any intermediate point.

It is also pdssible and desirable in some instances to have' the flash sustained throughout the range" of either the increasing or decreasing of the effectivel prism power, or it may be momentary at the points of maximum or minimum prism power.

Itis also possible and desirable in some instances to vary the pewer of the lenses 23| before the' eyes' tofcont'rl" accommodations during the above treatments.

The version treatment is introduced by using rotating targets having eccentric xation means thereon or with targetshaving the xation means exposed at 'varying points or with varying degrees of displacement of fixation points during the rotation thereof;4 and having the mirrors fixed at the position o'f veasy fusion of the targets or fixation-means.'

Retinal stimulations -for arnblyopic treatment are introduced mondcularly b'y the selection of suitable targets as to degree of size, shape or co'lor depending upon the degree of amblyopia, occluding the good eye and setting the flashing systenrsothat the source of illumination for the target will be successively ashed. In this instance', the' targets 4are lof the fined type.

The'` abo'vfe'treatment may be performed by the use of movable targets with different points oi xation. In this particular instance, there is no aslhfinglof the source of illumination.

The above mayy also bel performed with the use of ,movable targetscfernbined with the nashing.

'I'l'ieinte'nsity of illumination in any one of the kabove,'ca'ses should be suicient for the patient to View the trget, the intensity of illumination beingl controlledby either the rheostat |38 or |39, as thecse vmay be.

RetinalV stimulations may also be introduced witli'biii'ocular vision. In this instance, suitable targets are selectedA for each eye. The mirrors |28f are adjusted to compensate for anglel of squint and t'o obtain point of easy fusion. The flashing system Afor the sources of illumination maybe either s`et for synchronous or alternating flashing, 1a'sihas been previously described. In this` particular instance, the targets are of the nxfeu typ.'

The above treatment may also be performed with rotating targets" with fixed illumination.

Sterescoijctr'eatments may be performed by the selection of properrstationary stereoscopic or pseudoscp'ic targets, the' 'convergence or divergences beingcontroll'ed byadjustment of the angle of the mirrors" |28'. With the above arrangement, targetscan be' rotated to change the degree of stereoscopic or pseudoscopic effect. The ac commodatibn may also be controlled by the propenselection of'lense's 23|. The illumination may also be controlled as pretiously described above.

Accommdative treatments are introduced by the use of suitable targets for accommodation control and by the use of proper compensation lenses 23|. The above treatment may be performed with convergence or divergence and with illumination flashing.

Phoria tests are performed by the selection of proper fixed targets. In the instance of horizontal phoria, the accommodation is first controlled by the selection of proper accommodation lenses 23|, and vertical disassociation is compensated for by adjustment of the thumb nut 220. The images are then moved into alignment horizontally by adjustment of the angle of the mirrors through rotation of the thumb nut 2|IJ and the amount of adjustment to bring about this result is determined by taking readings from the scale and indicator means 206 and 201 to obtain the horizontal measurement.

The vertical phoria is obtained by rst disassociating the images of the iixed targets horizontally and by tilting the mirrors |28 through adjustment of the thumb nut 220 to tilt the mirrors vertically until the patient reports the images as being in alignment. The readings are taken from the scale and indicator means 22| and 222 to obtain the vertical measurement.

Tropia measurements are obtained by producing alternate fixations through the use of the flashing system. 'I'he mirrors are adjusted horizontally and vertically until all eye movements stop. 'I'he patients eye movements are preferably watched during the adjustments of the mirrors so as to be assured that the point of alignment of the images has been reached and that the eye movements have stopped. When this has been accomplished, the approximate angle of deviation is determined by reading the scale and indicator means 206 and 201 for the horizontal, and 22| and 222 for the vertical. You then inquire as to whether or not the patient sees both images in the same place. The procedure from then on is continued in the manner decided upon by the examiner. This is due to the fact that there are no fixed rules for th further procedure.

Disassociation technique is as follows: If the patient is amblyopic, (suppresses vision with one eye) an attempt is made to overcome suppression by moving the image viewed by the suppressing eye outside of the suppression area. The sources of illumination are then set to flash alternately or simultaneously until the patient reports vision in both eyes, or has definitely established simultaneous binocular vision. The prism power is then decreased horizontally or vertically to decrease the suppression area with a view to obtaining normal single binocular vision.

Duction measurements are obtained by adjusting mirrors, horizontally or vertically, until the patient obtains single binocular vision. The fusional amplitude in the horizontal meridian is determined by adjusting the mirrors horizontally to the innermost angle at which fusion can be maintained, or until the breaking point is reached, and by adjusting the angles of the mirrors to the outermost angle at which fusion can be maintained, or until the breaking point is reached. To obtain the vertical fusional amplitude, an eifective prism power is introduced vertically, base-up or base-down, by angling the mirrors in said directions until the breaking points are reached.

The above measurements may also be taken with varying degrees of accommodation or with vaccommodation relaxed by the proper selection of lenses 23| to approximate conditions for distant and near tests.

It is specifically pointed out that in all instances, the total eiective prism power, either base-up or base-down, base-in or base-out, is positively recorded during the operation of the machine and that the said effective prism power may be varied during the operation of the machine.

It is also pointed out that with the above described instrument, the flashings may be timed so as to occur at selected points during the swinging or oscillation of the mirrors and that this timing is changeable.

It is also to be understood that although there has been outlined herein certain techniques for obtaining tests, measurements or exercises, other treatments, tests, etc. may be performed or variations of said tests may be carried out. The above outlined techniques, methods of btaining measurements .and treatments have, however, been found very effective and beneficial and are at the present time preferable.

The flashings of the different sources of illurnination |29 and |29 have been described as being controllable during the continuously increasing or decreasing of the prism power be'- fore the eyes. f

This arrangement provides means whereby two distinctive exercises or treatments may be imparted to the eyes. The first of said treatments may be considered the less severe wherein the flashing of the illuminating means for each eye is controlled so that the sources of illumination are illuminated when the minimum prism power is before the eyes and the said illumination is sustained throughout the gradual increasing of the prism power to the maximum prism power at which instance the flashing mechanism turns oiT the illumination and allows the eyes to return to their position of rest or to a position similar to looking at infinity. During this period the prisms again return to the minimum point at which instance the sources of illumination are illuminated 'and the eyes are again carried through the treatment. 'I'his in eiTect causes the stress to be gradually increased and thence dropped when the maximum point is reached.

The second treatment is brought about by causing the sources of illumination to be illuminated at the instance of maximum prism displacement, at which point the eyes are called upon instantaneously to overcome the full stress of the treatment and the illumination is sustained throughout the range of gradual decreasing of the prism until a point of relaxation is reached, at vwhich point the illumination is turned oif throughout the period of the building up of the prism power to the maximum. The sources of illumination are then again illuminated to cause the eyes to be carried through the same treatment.

This latter method is more of a shock treatment.

It is of course to be understood that the flashing may be controlled so as to occur at different intervals intermediate the minimum and maxi'- mum prism displacement if desired, depending, of course, upon the nature of the treatment. For example, the illumination may be turned on at the point of minimum prism power and sustained during the increasing of the prism power to a predetermined amount intermediate the minimum and maximum points, at which point the sources of illumination will be turned off torender the fixation means viewed during said gradual increasing and decreasing of the prism power invisible. This condition, of course, might be reversed if desired.

By the above, it is apparent that there is a direct coordination between the ashing and prism vpower varying means and that the function of said ilashing and prism power varying means may be controlled separately although the said means operate automatically.

It will also be understood that the iiashings may be controlled to occur at predetermined instances during the manual varying of the prism power base-up or base-down introduced by tilting the mirrors.

It will be noted that the prism power is continuously increased or decreased, either base-in or out, up or down, without changing the effective position of the base or axis of theprism. This distinguishes from most prior art rotary prism devices which in effect do not increase the prism power before each eye but rotate the bases of the prisms to diiferent axes to change said prisms from a base-in to a base-out position or vice versa. Such devices do not enable the increasing and decreasing of prism power while maintaining the movement of the images displaced by said varying of the prism powerA along substantially a straight line. Rotary prism type devices, as set forth above, cause the images vto move in circular paths.

It is also pointed out that the increasing and decreasing of the prism power of the device embodying the invention is mechanically operated and functions with a smooth operating motion, the speed of which may be positively controlled.

A slot 234 is formed in the top of the instrument to provide means whereby the movements of the eyes may be viewed during the operation of the machine.

From the foregoing description, it will be seen that simple, efficient and economical means and method have been provided for accomplishing all of the objects and advantages of the invention, and more particularly means which may be quickly and accurately adjusted and methods and exercises which may be quickly and accurately performed.

Having described my invention, I claim:

l. In a myologic instrument, two mirrors arranged in angular relation, a test implement for each mirror brought into the field of vision by reflection from the mirror, means for automatically and constantly increasing and decreasing the angular relation of the mirrors in successive movements, and means moved by and with the mirrors for indicating the prism powerv of the mirrors in any one position thereof.

2. In a myologic instrument, two mirrors arranged in angular relation, a test implement for each mirror brought into the field of vision by reflection from the mirror, means for automatically and constantly increasing and decreasing the angular relation of the mirrors in successive movements, and means for automatically indi' eating the prism dioptry of the mirrors in any position.

3. A myologic instrument including two mirrors supported for movement relative to a common pivot in divergent relation, test implements brought into the eld of vision by reflection from the mirrors, means for automatically and progressively increasing and decreasing alternately thedivergence of the mirrors to'correct abnorvmalhorizontal balance of vision, and means to selectively incline the pivot to alter the normal horizontal plane of the mirrors to correct abnormal vertical balance of vision.

Y 4. A myologic instrument including two mirrorssupported for movement relative to acommon pivot in divergent relation, test implements brought into the iield of vision by reflection from the mirrors, means for automatically and progressively increasing and decreasing alternately the divergence of the mirrors to correct abnormal horizontal balance of vision, means to selectively incline the pivot to alter the normal horizontal plane of the mirrors to correct abnormal vertical'balance of Vision, and dioptric scales for measuring each increment of mirror movement.

5. In a myologic instrument, two mirrorsgarranged for independent movement with respect to a commonaxis, a test element for each mirror brought into the field of vision by reflection from the mirror, means for automatically and constantly varying the angular relation of the mirrors in regular movement, and meansrfor directly varying the inclination of the axis of the mirrors and thereby changing the respective planes in which they operate.

6. In' a myologic instrument, two mirrors mounted in angular relation with respect to a common swinginglymounted pivot,a test element for each mirror brought into the field of vision by reflection from the mirror, means for constantly and regularly varying the inclination of the mirrors for varying the prism power, land means for varying the inclination of the common pivot to change the relative vertical planey of the mirrors.

'7. A myologic instrument including two mirrors supported for movement relative to a common point in divergent relation, test implements brought into the field of vision by reilection from the mirrors, means for automatically and progressively increasing and decreasing alternately the divergence of the mirrors to correct abnormal horizontal balance of vision, andv means for altering the normal horizontal plane of the mirrors to correct abnormal vertical balancev of vision. i

8. A myologic instrument including two mirrors supported for movementV relative to a common point in divergent relation, test implements brought into the eld of vision by reflection from the mirrors, means for automatically and progressively increasing and decreasing alternately the divergence of the mirrors to correct abnormal horizontal balance of vision, means for i altering the normal horizontal plane of the mirrors to correct abnormal vertical balance of vision, and dioptric scales for measuring each increment of mirror movement. e

9. In a myologic instrument, two mirrors mounted vfor independent swinging movement from a vcommon point, test implements brought into the iield of vision by reflection from both mirrors, a power means, a connection between the power means and each mirror, said connection operating under the power means to swing the mirrors alternately in opposite directions to compel'a minimum and maximum limit of mirror divergence in any two successive mirror movements, and means to manually adjust the mirrors relative to each other to selectively predetermine the limit-of minimum and maximum divergence of the mirrors during operation of the power means.

1Q. AV myologic instrument comprising two mirrors mounted for independent Swinging mcvef ment from a common point, test implements brought into the field of vision by mirror reection, a power means, a connection rbetween the power means and mirrors, said connection comprising operating under the power means to swing the mirrors simultaneously in relatively opposite directions to compel a maximum and minimum limit of mirror divergence in any two successive mirror movements, the variation in mirror divergence serving to vary the prism power to which the vision is subjected, and means for manually adjusting the power means to cause said connections to vary the minimum divergence of the mirrors at will.

l1. In a myologic instrument, two mirrors mounted for independent movement from a common point and having a normal minimum divergence when at rest, a test implement for each mirror brought into the field of vision by reflection from the mirror, means for automatically and constantly varying the angular relation of the mirrors in directly successive movement, and means for varying the extent of the mirror movement.

12. In a myologic instrument, two mirrors mounted for independent swinging from a common point, a moving test implement for each mirror brought into the field of vision by reflection from the mirrors, means for automatically and constantly Varying the angular relation of the mirrors in directly successive movement to thereby constantly vary the lprism power from a minimum to a maximum, and means for varying the speed of mirror movement while maintaining the movement of the test implements constant.

13. An ophthalmic instrument for use with a persons eyes comprising a pair of light deecting members, one before each eye, a test implement for each light deflecting member brought into the eld of vision by deection resulting from said light deiiecting members for aiding the eyes in obtaining single binocular vision of the images of said test implements, means for automatically and constantly increasing and decreasing the angle of deection of said light deecting means to alter the relation of the images and means associated with said light deflecting means for indicating the angle of deflection in any one position of displacement of said images.

14. An ophthalmic instrument for use with a persons eyes comprising a separate test implement for each of the respective eyes of the person, means for illuminating said test implements, a pair of light deflecting members, one before each eye, for bringing images of the test implements into the eld of vision to aid the eyes in obtaining single binocular vision of said images, means for automatically and constantly increasing and decreasing the angle of deflection of said light deflecting means to alter the relation of the images, means associated with said light delecting means for indicating the angle of deflection in any one position of displacement of said images and means for turning on and shutting off said illumination at predetermined intervals during said displacement of said images.

l5. An ophthalmic instrument for use with a persons eyes comprising a pair of light deflecting members, one before each eye, a test implement for each light deflecting member brought into the field of vision by deection resulting from said light deflecting means for aiding the eyes in obtaining single binocular vision of the images of said test implements, means for automatically and constantly increasing and decreasing the angle of deection of said light deecting means to alter the relation of the images and means associated with said light deflecting means' for indicating the angle of deflection in any one position of displacement of said images, and means for moving said test implements in given controlled paths during displacement of the images thereof by the light deflecting members.

WORTHY C. HARPER. 

